Abad Santos was appointed Secretary (later Minister) of Justice by PresidentFerdinand Marcos in 1970. He would serve in that capacity until January 1979. As early as June 1977, he was appointed to the Supreme Court, but he deferred accepting the appointment until January 17, 1979, when he was finally seated on the High Court.
Long viewed as a supporter of Ferdinand Marcos, he displayed considerable independence from the Marcos government once he was seated on the Supreme Court. By 1986, he was asked by the anti-Marcos opposition to swear into office Corazon Aquino's vice-presidential candidate Salvador Laurel at the height of the EDSA Revolution.[2] When Aquino assumed the presidency on February 25, 1986, she asked for the resignation of the incumbent justices of the Supreme Court to allow her a free hand in reorganizing the Court. Abad Santos and fellow incumbent Justice Claudio Teehankee were the President's first two appointments to the reorganized Supreme Court. However, Abad Santos retired shortly after, in July 1986, upon reaching the mandatory retirement age of 70.
Sevilla, Victor J. (1985). Justices of the Supreme Court of the Philippines Vol. III. Quezon City, Philippines: New Day Publishers. pp. 137–138. ISBN971-10-0139-X.